1 /*        $NetBSD: interp_backslash.c,v 1.3 2009/07/20 04:59:03 kiyohara Exp $  */
2 
3 /*-
4  * Redistribution and use in source and binary forms, with or without
5  * modification, are permitted provided that the following conditions
6  * are met:
7  * 1. Redistributions of source code must retain the above copyright
8  *    notice, this list of conditions and the following disclaimer.
9  * 2. Redistributions in binary form must reproduce the above copyright
10  *    notice, this list of conditions and the following disclaimer in the
11  *    documentation and/or other materials provided with the distribution.
12  *
13  * Jordan K. Hubbard
14  * 29 August 1998
15  *
16  * Routine for doing backslash elimination.
17  */
18 
19 #include <sys/cdefs.h>
20 /* __FBSDID("$FreeBSD: src/sys/boot/common/interp_backslash.c,v 1.6 2003/08/25 23:30:41 obrien Exp $"); */
21 
22 #include <lib/libsa/stand.h>
23 #include <lib/libsa/loadfile.h>
24 #include <lib/libkern/libkern.h>
25 
26 #include "bootstrap.h"
27 
28 #define DIGIT(x) (isdigit(x) ? (x) - '0' : islower(x) ? (x) + 10 - 'a' : (x) + 10 - 'A')
29 
30 /*
31  * backslash: Return malloc'd copy of str with all standard "backslash
32  * processing" done on it.  Original can be free'd if desired.
33  */
34 char *
backslash(char * str)35 backslash(char *str)
36 {
37     /*
38      * Remove backslashes from the strings. Turn \040 etc. into a single
39      * character (we allow eight bit values). Currently NUL is not
40      * allowed.
41      *
42      * Turn "\n" and "\t" into '\n' and '\t' characters. Etc.
43      *
44      */
45     char *new_str;
46     int seenbs = 0;
47     int i = 0;
48 
49     if ((new_str = strdup(str)) == NULL)
50           return NULL;
51 
52     while (*str) {
53           if (seenbs) {
54               seenbs = 0;
55               switch (*str) {
56               case '\\':
57                     new_str[i++] = '\\';
58                     str++;
59                     break;
60 
61               /* preserve backslashed quotes, dollar signs */
62               case '\'':
63               case '"':
64               case '$':
65                     new_str[i++] = '\\';
66                     new_str[i++] = *str++;
67                     break;
68 
69               case 'b':
70                     new_str[i++] = '\b';
71                     str++;
72                     break;
73 
74               case 'f':
75                     new_str[i++] = '\f';
76                     str++;
77                     break;
78 
79               case 'r':
80                     new_str[i++] = '\r';
81                     str++;
82                     break;
83 
84               case 'n':
85                     new_str[i++] = '\n';
86                     str++;
87                     break;
88 
89               case 's':
90                     new_str[i++] = ' ';
91                     str++;
92                     break;
93 
94               case 't':
95                     new_str[i++] = '\t';
96                     str++;
97                     break;
98 
99               case 'v':
100                     new_str[i++] = '\13';
101                     str++;
102                     break;
103 
104               case 'z':
105                     str++;
106                     break;
107 
108               case '0': case '1': case '2': case '3': case '4':
109               case '5': case '6': case '7': case '8': case '9': {
110                     char val;
111 
112                     /* Three digit octal constant? */
113                     if (*str >= '0' && *str <= '3' &&
114                         *(str + 1) >= '0' && *(str + 1) <= '7' &&
115                         *(str + 2) >= '0' && *(str + 2) <= '7') {
116 
117                         val = (DIGIT(*str) << 6) + (DIGIT(*(str + 1)) << 3) +
118                               DIGIT(*(str + 2));
119 
120                         /* Allow null value if user really wants to shoot
121                        at feet, but beware! */
122                         new_str[i++] = val;
123                         str += 3;
124                         break;
125                     }
126 
127                     /* One or two digit hex constant?
128                      * If two are there they will both be taken.
129                      * Use \z to split them up if this is not wanted.
130                      */
131                     if (*str == '0' &&
132                         (*(str + 1) == 'x' || *(str + 1) == 'X') &&
133                         isxdigit(*(str + 2))) {
134                         val = DIGIT(*(str + 2));
135                         if (isxdigit(*(str + 3))) {
136                               val = (val << 4) + DIGIT(*(str + 3));
137                               str += 4;
138                         }
139                         else
140                               str += 3;
141                         /* Yep, allow null value here too */
142                         new_str[i++] = val;
143                         break;
144                     }
145               }
146               break;
147 
148               default:
149                     new_str[i++] = *str++;
150                     break;
151               }
152           }
153         else {
154             if (*str == '\\') {
155                 seenbs = 1;
156                 str++;
157             }
158               else
159                     new_str[i++] = *str++;
160         }
161     }
162 
163     if (seenbs) {
164         /*
165          * The final character was a '\'. Put it in as a single backslash.
166          */
167           new_str[i++] = '\\';
168     }
169     new_str[i] = '\0';
170     return new_str;
171 }
172